Dotsenko V. Borates of group II-III elements: synthesis - electronic structure - luminescent properties

Object of investigation: borates of group II-III elements. Aim of investigation: establishment of the regularities in series: composition - crystal structure - electronic structure - luminescence properties of borates of group II-III elements, development of the principles for their direct activation, and obtaining new effective luminescent materials. Methods of investigation: X-ray (diffractometer DRON-2), thermal analysis (Q-1000), luminescence analysis (spectrometers SDL-1, MDR-23), NMR (spectrometer Bruker MSL-400), IR spectroscopy (spectrophotometer Perkin Elmer 21), Raman spectroscopy (spectrometer DFS-24), diffuse reflection spectroscopy (spectrophotometer Perkin Elmer Lambda 9), electronic vibration spectroscopy. The systematic study of regularities in a series: composition - crystal structure - electronic structure - luminescence properties of borates of group II-III elements has been performed. The borate-anion group is found to determine the valence-band electronic structure of alkaline earth and rare earth borates. It was shown that the differences in the structure of boron-oxygen network affect essentially the characteristics of luminescent centers. The possibility of quantitative description of the influence of borate-anion type on the luminescent properties of lanthanide ions in frame of the electronegativity concept has been demonstrated. The microstructure of luminescent centers and the mechanisms for charge compensation for lanthanides Ln(III) in alkaline earth haloborates of composition M2B5O9X (M=Ca, Sr, Ba; X= Cl, Br) and magnesium fluoroborates (Mg2BO3F, Mg5(BO3)3F3, Mg3BO3F3) were established for the first time. It was shown that the stability of divalent lanthanides Ln(II) (Ln= Sm, Eu, Yb) in alkaline earth borates depends on condensation degree of borate anions. The new compounds with mixed oxide anions La4BVO10, LaB2TaO7 have been found, and the factors determining their luminescence properties have been ascertained. The new materials for information imaging devices and thermal neutron detection systems have been developed. Degree of application: semi-industrial tests in Ukrainian State Science-investigation Institute of Received Electronic Rays Tubes "Erotron" (c. L'viv) and Science Industrial Corporation "Gasotron" (c. Rivne). Field of application: inorganic chemistry, electronic industry